People who get things done: talk big first, then act
If you don't make commitments upfront, and don't hold people accountable during execution, your boss will see you as unreliable.
You don't seem confident you can win, you don't seem sure you can hit your targets or KPIs. That's all he'll think.
What does "no confidence" mean? It means your return is uncertain.
We buy a lottery ticket for $2 and might win $5 million. But if someone sells one for $1 million, would you buy it? No, because you know there's no guarantee. When it's pure luck with no certainty, you won't pay much.
Your boss sees you the same way: if he feels uncertain about you, he'll think you're not worth much.
People who get things done do this: brag first, then deliver.
Once you've bragged big, you can demand resources. With enough resources stacked up, maybe sheer manpower will carry you through. What if it still doesn't work out? Whatever. Success becomes your boss's wealth; failure becomes your personal wealth.
You've already led a major project. Even if it failed, that experience makes you a rare talent in the industry. Other bosses will think: someone already paid to train you. They'll poach you, you learn from your former boss's mistakes, and maybe you'll help them win.
That's what they mean by: success is your boss's wealth, failure is your personal wealth—it's how you sell yourself at a better price.
Why are you here? Who do you want to become when you leave?